ISHS Acta Horticulturae 713: VI International Peach Symposium
GENETIC CONTROL OF INTERNAL BREAKDOWN IN PEACH |
| Authors: | C.P. Peace, C.H. Crisosto, D.T. Garner, A.M. Dandekar, T.M. Gradziel, F.A. Bliss |
| Keywords: | mealiness, browning, bleeding, endopolygalacturonase, freestone, melting flesh, cold storage |
| DOI: | 10.17660/ActaHortic.2006.713.73 |
| Abstract:
Internal breakdown (IB), also known as chilling injury, is the collective term for various disorders that occur during prolonged cold storage and/or after subsequent ripening of stone fruit. Symptoms include mealiness, flesh browning, loss of flavor, and red pigmentation (bleeding). The problem is usually not noticed until fruit reaches consumers, reducing demand. Some cultivars tend to be more susceptible than others, indicating a significant genetic component underlying expression of the symptoms. With an improved understanding of this genetic component, strategies could be implemented for breeding new cultivars with low IB susceptibility. We have undertaken a classical and molecular genetics approach to search for controlling genes, using two related progeny populations of peach. Each IB trait had a high heritability in the populations, with relatively small seasonal or rootstock effects. Endopolygalacturonase (endoPG) was determined to play a qualitative role in the development of mealiness, as a functional endoPG gene must be present for the expression of other genes that influence mealiness susceptibility. Despite the control by endoPG of the Melting flesh trait in the late stages of normal fruit ripening, its enzymatic action leading to mealiness may instead occur during cold storage. The F-M/endoPG locus also had a large effect on the development of bleeding. A major QTL was identified for browning elsewhere in the genome. These results, combined with discontinuous trait distributions, suggest that there may be only a few major genes controlling each of the IB symptoms. EndoPG is the first of these genes for mealiness and probably bleeding also. Finding further genes and developing marker-assisted selection for IB in peach appear to be achievable goals. | |
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